William d



'W'. 9 HEYER.

SCHOOL SLATE.

No. 297,996. Patented May 6.1884;

UNITED STATES PATENT QEFICEO WILLIAM B. HEYER, on ELIZABETH, NEW JERSEY.

SCHOOL-SLATE.

SPECIFICATION forming part of Letters Patent No. 297,996, dated May 6, 1884.

Application filed September 10, 1883.

To all whom it may concern.-

Be it known that 1, WILLIAM D. HEYER, a citizen of the United States, residing atElizabeth, in the county of Union and State of New Jersey, have invented. a new and useful Trac ing School-Slate, of which the following is a specification.

My invention consists in combining a piece of ground glass with an ordinary slate in such a manner that drawings or written copies made upon the slate can be traced upon the ground glass with an ordinary slate-pencil, the white lines made by theslate-pencil being rendered visible by the dark background afforded by the slate. In the same manner printed cards containing designs in white lines upon ablack ground may be inserted underneath the glass and traced with a slate-pencil. I attain these results by the means illustrated in the accompanying drawings, in which Figure l is a top view of the slate with the ground glass lying flat upon the surface; and Fig. 2 is a longitudinal section on the line a b, Fig. 1, with the glass raised.

Similar letters refer to similar part-s in each View.

A, Fig. 1, shows the surface of an ordinary school-slate partitioned into two-portions by the strip 13. One portion is covered by a rectangular piece of ground glass, 0, having its rough surface uppermost, which is fastened to the slate-frame by a flexible hinge, In Fig. 2 this piece is represented as raised from the slate, to allow of cards being slipped under- 3 5 neath, or drawing or writing being made upon the slate-surface.

I do not limit myself to attaching the glass (No model.)

to the slate by a hinge, as it may be arranged to slide in'a groove, or in any other suitable manner; nor do I limit myself to making the 40 tracing-surface of glass, as any suitable translucent material having a roughened surface may be substituted.

The manner of using my invention is as fol lows: The ground glass 0 being raised, as shown in Fig. 2, a drawing or writing copy is made with a slate-pencil upon the portion of the slate lying underneath the glass, or else a black card having a design upon it in white is laid upon the slate-surface. The ground glass is then lowered upon the design, and it may then be traced upon the rough surface of the glass with an ordinary slate-pencil.

I am aware that transparent slates for tracing with lead-pencil have been devised, and have been combined with opaque slates especially constructed for that purpose; but I am not aware that atracing-slate has been so combined with an ordinary school-slate as to admit of drawings made upon the surface of the school-slate being traced upon the transparent slate with a slate-pencil, thus adapting it for use in primary schools, where the use of a lead-pencil is inconvenient.

What I claim as my invention, and desire to secure by Letters Patent, is

A school-slate, in combination with a transparent slate hinged thereto, so as to cover or uncover a portion of the opaque slate, substantially as described.

- WILLIAM D. HEYER.

Witnesses:

K. M. WARNER,

'STEPI-IEN H. POWELL. 

